refraction of human eye

The human eye uses light and enables us to see objects around u..

You must have seen some people holding books very close to their eyes. This is because they suffering from myopia (short sightedness). A myopic person cannot see distant objects clearly because the far point of his eye is less than infinity. Myopia is an eye defect du..

It is a biconvex, circular, transparent object located just behind the pupil. It serves to focus the light on the retina. It is an elastic structure and its shape can be varied to adjust to objects at varying distances. The adjustment is made with the help of muscles. The lens is held in place..

Hypermetropia - You must have seen middle aged people holding a book away from their eyes to read properly. This is because they are not able to see the nearby objects clearly. We say that those people are suffering from hypermetropia (long sightedness). Hypermetropia or hyperopia is an h..

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The twinkling of stars is due to atmospheric refraction of starlight. Since light bends towards the normal the apparent position of the star is slightly different from its actual position as it passes through the atmosphere. Hence the star appears slightly higher than its actual position...

Shortening of the eyeball, that is, the eyeball becomes smaller Increase in focal length of the eye lens Let us now see how this defect is rectified. A long sighted eye forms image of a nearby object behind the retina. Thus, long sightedness is due to the decreased conver..

Every cell, whether it is prokaryotic or eukaryotic, is enclosed in a thin covering called cell membrane. It is also called as plasma membrane or plasma lemma. The cell membrane can only be seen through the electron microscope since its thickness is well below the resolving power of huma..

1) Observer must stand with his back towards the sun. The common centre of the concentric circular arc lies on the line joining the sun to the eye of the observer. The brightest bow seen is the primary rainbow, which is formed due to one total internal reflection and two refractionh..

The endocrine gland attached to the roof of third ventricle in the rear portion of brain, is known as the pineal gland, named for its resemblance to a pine cone. It has no direct connection with central nervous system. It is variable in size and weighs about 150 mg, but it is richly vascularised an..